1. Field of the Invention
The present invention relates to a snap fit mechanism used for securing a component provided, for example, in a disk playback device.
2. Description of Related Art
For example, JP-A 08-111157 (claim 1 and FIG. 5) discloses a conventional snap fit mechanism of the type to which the present invention relates, provided in an electrical appliance and its attachment. The conventional snap fit mechanism known to the inventor is composed of a first engaging portion provided on the electrical appliance side and a second engaging portion provided on the case (serving as its attachment) side. The first engaging portion includes a concave portion formed on the sidewall of the electrical appliance and a pair of protrusions that are formed within the concave portion and reduces the opening space of the portion. The second engaging portion includes an elastic tongue that is projected from one plane face of the case and that has a pair of engaging claws formed at the tip of the tongue, elastically engaging the pair of protrusions provided in the first engaging portion, respectively. Each of the engaging claws is composed of a sideward face, which extends sideward from the tip of the elastic tongue and secures the electrical appliance between the one plane face of the case and the sideward face itself, and an inclined face, which extends across the end of this sideward face, which is remote from the elastic tongue, and the tip of the elastic tongue. Moreover, at the tip of the elastic tongue is provided a top face having a plane face that is orthogonal to a longitudinal direction of the elastic tongue and that is connected with the extreme end of the inclined face of the engaging claw.
The operation will now be described as below.
First of all, on securing the to-be-secured member (attachment) in the electrical appliance, when the case (serving as the attachment) is made to approach the electrical appliance to thereby make the extreme end of the inclined face of the engaging claw contact the protrusion of the electrical appliance, and then the protrusion of the electrical appliance is made to slide from the extreme end of the inclined face thereof to the case side along the inclined face of the engaging claw, the elastic tongue is elastically deformed to the side opposite the engaging claw (that is, inwardly from the elastic tongue) in accordance with this sliding movement. When the case is further pressed against the protrusion of the electrical appliance, the tip of the engaging claw, that is, the end of the sideward face thereof goes across the protrusion of the electrical appliance. At that time, the elastic tongue recovers to its original posture by the restoring force exerted by its elasticity, thereby securing the electrical appliance between the one plane face of the case and the sideward face of the engaging claw.
However, because the conventional snap fit mechanism is configured as mentioned above, there has been the following problem when the mechanism is applied for securing a tabular component, for example, in a disk playback device. The elastic tongue of the conventional snap fit mechanism is inserted into the through hole of the tabular component, and then the engaging claw of the elastic tongue is engaged with the edge of the through hole thereof, thereby enabling securing of the tabular component in the device. However, after securing the tabular component therein, when, for example, a worker's finger or the like at assembling work contacted the tip of the elastic tongue, which is exposed from the through hole, the elastic tongue may be inwardly elastically deformed by the load received on the inclined face of the engaging claw. This is because at the tip of the elastic tongue is formed a top face, and the inclined face of the engaging claw is formed adjacent to this top face. As a result, there is a problem that at that time the engaging claw snaps out of the edge of the through hole of the tabular component, and thereby the engagement of the existing snap fit mechanism with the tabular component is accidentally released.